Grouting Material Research Articles

Research on the Rheological Properties and Diffusion Law of Coal-Based Solid Waste Geopolymer Grouting Material

Research on the Rheological Properties and Diffusion Law of Coal-Based Solid Waste Geopolymer Grouting Material

Influence of glass beads on alkali-activated slag-metakaolin-based novel grouting materials: Physical properties, leaching kinetics and microstructure

Influence of glass beads on alkali-activated slag-metakaolin-based novel grouting materials: Physical properties, leaching kinetics and microstructure

Study on the fluid-solid transition mechanism of natural hydraulic lime pastes: Consider the water to binder ratio and polycarboxylate superplasticizer

Natural hydraulic lime (NHL) is used as a grouting material in the restoration of ancient buildings, the formation and evolution of its early workability are crucial for the reliability of the restoration effects. This paper conducts an in-depth study on the effects of water to binder (w/b) ratio and polycarboxylate superplasticizer (SP) dosage on the viscoelastic properties of fluid-solid transition process in NHL paste through tests on the fluidity, rheological characteristics, micro-rheology, hydration heat release, and early phase composition. The results show that the fluidity of NHL paste significantly increases with increasing w/b ratio and SP dosage, while its yield stress and plastic viscosity show downward trend, and it has shear thinning characteristics. In the initial stage, elevated w/b ratio leads to the significant reduction in both macroscopic viscosity index (MVI) and elastic index (EI) of NHL paste, along with delayed rapid increases, the effect is even more pronounced by adding SP. High w/b ratio or adding SP are able to enhance the dispersed state of solid particle in NHL pastes, the viscoelastic transition point of NHL paste is delayed and the viscoelastic transition time is prolonged. Increasing the w/b ratio and adding SP both inhibit the early dissolution and hydration of NHL paste, affecting the fluid-solid transition process. Overall, as the spatial network gradually develops by the solid particles dissolve and continue to hydrate, NHL paste undergoes a transition from a viscous fluid to an elastic semi-fluid state, exhibiting low strength and noticeable plasticity characteristics. With further hydration, NHL paste initiates consolidation and hardening processes, progressively transforming from a plastic semi-fluid into hardened paste.

Enhancement behaviours of carbon nanotubes reinforced cement based grouting materials under dynamic loading

Carbon nanotubes (CNTs) reinforced cement based grouting material is an important part of green manufacturing industry. Our previous research showed that this material can effectively enhance the impact resistance of rock matrix. In this study, We conducted a comprehensive study and quantitative analysis of the changes in pore structure of this material under impact conditions. Dynamic impact testing and computed tomography (CT) revealed that CNTs significantly increased the cement content in the sample by 79.11%. The CNTs group exhibited higher internal pore density and uniformity, effectively suppressing the formation of dynamic cracks in the sample. Compared to Non-carbon nanotubes (Non-CNTs) cement-based materials, the peak dynamic stress of the CNTs group increased by 4.76% to 21.54%, while the porosity decreased by 57.26%.This study further refined the enhancement behaviors of carbon nanotubes reinforced cement based, and making outstanding contributions to engineering practice.

Chemical and electrochemical repair methods for the anchorage regions of grouted, post-tensioned concrete systems

Grouted, post-tensioned concrete systems are commonly used for constructing bridges with an intended corrosion-free service life of 100+ years. However, the use of inadequate grout materials and improper grouting techniques have caused voids at the anchorage regions – resulting in premature corrosion (say, within one or two decades) of strands. In addition, re-grouting the voids with repair grout has aggravated the corrosion of strands at the interface between the base grout (usually carbonated) and repair grout due to the differences in their chemical properties – raising concerns and leading to reluctance in re-grouting the voids in tendons. This work focused on developing non-invasive chemical (re-alkalization) and electrochemical (galvanic cathodic protection) methods to repair the anchorages of grouted, post-tensioned concrete systems. Immersion experiments were conducted to assess the efficiency of alkaline solutions in re-alkalizing the carbonated grouts. It was found that 1M Ca(OH)2 solution can restore the pH of the carbonated grouts in about a day. Moreover, the electrochemical impedance spectroscopy studies indicated that 1M Ca(OH)2 solution can re-passivate the embedded strands within a week. It can be sometimes challenging to achieve complete re-alkalization and re-grouting of voids; hence, a redundant electrochemical system that could work from outside the anchorage was found necessary. Therefore, experiments were conducted to evaluate the viability of galvanic anodes in protecting the anchorages. It was found that a thin layer of grout surrounding the strand would be sufficient to provide ionic conductivity for the galvanic anode (connected to the strand-end outside the anchorage) to protect the strand portions inside the anchorage. Based on the study, recommendations for the repair of the anchorage regions using chemical and electrochemical methods are presented.

Research on the Mechanical Properties of Composite Grouting Materials Based on Ordinary Portland–Sulphoaluminate Cement

This study aimed to enhance the mechanical properties of calcium sulfoaluminate cement grouting materials (HCSA) by investigating the effects of ordinary Portland cement (OPC) content, the ratio of quicklime to gypsum, and the dosage of sodium aluminate on the compressive strength of the OPC-CSA composite system. The results indicate that as the OPC content increases, the compressive strength of the blended cement initially increases and then decreases, reaching a maximum at a 60% OPC replacement ratio within the experimental group. The addition of an appropriate amount of OPC to the CSA composite system effectively prevents the regression of compressive strength. With an increase in quicklime content, the compressive strength of the samples at various ages first increases and then decreases, with the optimal ratio of quicklime to gypsum found to be 2:8. Furthermore, sodium aluminate, used as an activator, when increased in dosage, leads to an initial increase followed by a decrease in the compressive strength of OPC-CSA samples, with an optimal incorporation rate of 0.75%, significantly enhancing the strength of the blended cement. In the orthogonal experiments, the dosage of sodium aluminate was identified as the most influential factor affecting the compressive strength of the composite grouting materials.

Study on the strength influence mechanism and cracking mechanism of stone powder-cement floor grouting materials

Underground grouting is a concealed project, and it is difficult to test the strength of grouting stones in engineering practice. Aiming at the problems of high confined water pressure and strong water-richness of the roadway floor, a pressure filtration test device was developed, and a PFC2D uniaxial compression model was established to study the variation law of stone strength and crack evolution mechanism of grouting materials under different grouting pressures. The results show that with the increase of pressure filtration value, the amount of slurry dehydration increases, the pore water pressure dissipates, the pores between particles are tightly compressed, the contact force between particle skeletons increases, and the strength of stone body increases. Under the condition of the same cement powder ratio (mass ratio of cement to stone powder) or stone powder particle size, the strength of stone body of stone powder-cement grouting material increases with the increase of pressure filtration value. The stress-strain curves of the stone body with different pressure filtration values all experienced three stages: continuous elasticity, fracture expansion and strength failure. Before the peak, the number of cracks increases slowly; after reaching the peak, the micro-cracks extend rapidly and the number increases rapidly, resulting in the final tensile failure of the specimen. This study can provide a basis for the selection of grouting engineering material ratio and grouting pressure parameters.

Study on Engineering Properties and Mechanism of Loess Muck Grouting Materials

Shield tunneling generates a massive amount of muck, and achieving the on-site reuse of muck is an urgent need in the field of shield tunneling. This study, based on a section of the Xianyang diversion tunnel in a loess stratum, aims to optimize the mix ratios of loess muck grouting materials to meet specific performance requirements. Laboratory tests were conducted to analyze the effects of the bentonite content and water–solid ratio on the properties of grout. The engineering properties, cost, and environmental impact of the optimized loess muck grouting materials were compared with those of traditional grouting materials. Additionally, XRD, SEM, and CT were employed to investigate the solidification mechanism of loess muck grouting materials. The results show that the bleeding rate, setting time, fluidity, and consistency of loess muck grouting materials decreased with increasing bentonite content, while these properties increased as the water–solid ratio rose. The compressive strength reached 0.26 MPa and 1.05 MPa at 3 d and 28 d, respectively. Compared to traditional grouting materials, the economic cost and carbon emissions of loess muck grouting materials were reduced by 49.46% and 37.17%, respectively. As the curing time increased, gel filling and particle agglomeration reduced the number of pores. The dense microstructure is the primary factor for the improvement of strength.

Durability of a Metakaolin-Incorporated Cement-Based Grouting Material in High Geothermal Tunnels

Durability of a Metakaolin-Incorporated Cement-Based Grouting Material in High Geothermal Tunnels

Research on the connection performance and micro-hydration mechanism of super-performance grouting material for prefabricated component connections

Abstract The performance of grouting material determines the connection reliability of prefabricated components and the overall safety of the structure. In order to realize the rapid connection of prefabricated components, improve the construction efficiency and improve the quality of component connection. The research group has developed a grouting material with fast early strength improvement and high late strength. The formation mechanism was analyzed by scanning electron microscopy. The reliability of grouting material was verified by uniaxial tensile test of sleeve grouting connector. The results show that : CH, AFt and C-S-H are formed inside the grouting material, and the cementing system is dense inside. The skeleton formed by AFt inhibits the shrinkage of the system, which can provide support for the later compressive and flexural strength. Uniaxial tensile test results and theoretical analysis. The external reinforcement of the sleeve is broken, and the bonding performance between the grouting material and the reinforcement inside the sleeve is reliable. The internal bond stress is far less than the failure stress of the connector, which is about 50 % of the failure stress.

Seismic Behavior of Concrete Beam-Column Joints Reinforced with Steel-Jacketed Grouting

Joints in frame structures often fail before beams and columns in an earthquake and are a key part of reinforcement. In this study, to enhance the seismic performance of concrete frame structures, a steel-jacketed grouting composite reinforcement method is proposed by combining reinforcement technology, steel cladding technology, and eco-efficient materials from grouting technology. This method effectively utilizes the advantages of various materials, avoids major demolition and construction, and reduces waste and resource consumption. In order to verify the feasibility and effectiveness of the reinforcement method, one of the original joint specimens with a scale of 1:3 and one of the reinforced joint specimens were designed and tested. The experiments involved reversed cyclic testing of beam–column to measure its seismic behavior. The seismic performance indexes such as failure characteristics, hysteretic properties, and the energy dissipation capacity of the specimens were analyzed, and the corresponding finite element model was established. The influence of key parameters such as reinforcement range, steel plate thickness, and grout strength on its seismic performance was explored. The research shows that the method can effectively improve the seismic performance of the joints, and seismic performance indexes such as bearing capacity, ductility, and energy consumption of the specimens are significantly improved. The test results of the established finite element model are in good agreement. The variable parameter analysis of the finite element shows that the thickness of the steel plate has little influence on its bearing capacity. With the increase in the reinforcement range of the clad steel and the strength of the grouting material, the bearing capacity of the specimen increases. The research results can provide a reference for the reinforcement of frame structure joints.

Evaluating the effects of cement asphalt emulsion paste as a grouting material on the fatigue and thermal contraction properties of semi-flexible asphalt composite pavement

Semi-flexible asphalt (SFA) composite pavement is widely used in pavement engineering for its high load-bearing capacity, enhanced durability, impermeability, and resistance to fuel and oil spillage. However, its cracking resistance remains a concern, influenced by repeated vehicle loads and thermal contraction stresses. This study investigates the impact of cement asphalt emulsion paste as a grouting material on SFA’s fatigue and thermal contraction. SFA specimens were grouted with cement paste (CP) containing 20%, 40%, and 60% asphalt emulsion. These specimens were subjected to indirect tensile strength, resilient modulus, and fatigue tests, along with evaluation of thermal contraction behavior using coefficient of thermal contraction. Results indicated that adding asphalt emulsion to CP enhances the flexibility and ductility of SFA but reduces its indirect tensile strength and stiffness modulus. A mathematical model was introduced to predict the resilient modulus based on indirect tensile strength tests. The fatigue analysis demonstrated significant difference in fatigue resistance between SFA and AC16 materials. Incorporating asphalt emulsion also improved SFA’s thermal contraction behavior.

Performance evaluation of high early strength micro-expansion geopolymer grout potentially used for sustainable road infrastructure

This study aimed to develop a high early strength micro-expansion geopolymer grout material derived from recycled concrete and ground granulated blast-furnace slag (GGBS), which can be used to fill the subgrade voids and strengthen weak subgrade. A series of grout materials with varying proportions of recycled concrete were prepared, and their setting time, flowability, and strength characteristics were evaluated. The results indicated that the grout material containing 50 % recycled concrete had a final setting time of 29 min, a flow time of 15.2 s, and a 7-day compressive strength of 40.6 MPa, all of which met the requirements for subgrade grout materials. To further enhance the performance of the grout, the additives including 2 % calcium chloride (CaCl2), 5 % magnesium oxide (MgO), and 5 % united expansive agent (UEA) were used. Results showed that the samples containing 50 % recycled concrete and 2 % CaCl2 exhibited a 26.5 % increase in strength after 100 min of curing, while MgO and UEA reduced shrinkage by 112.5 % and 90.0 %, respectively. Additionally, microstructural analysis using SEM and XRD provided valuable insights into the complex interactions between components and their effects on material integrity. The results demonstrated that the use of CaCl2 accelerated the hydration reaction, enhancing early strength, while the expansion agents MgO and UEA mitigated shrinkage and achieved micro-expansion at low concrete content. This study addresses environmental concerns by incorporating recycled materials, positioning the developed geopolymer grout as a sustainable, high-performance alternative in road construction. Integrating waste-derived components and innovative additives represents a significant step towards advancing sustainable practices in infrastructure development.

A prestressed anchor-grouting reinforcement method based on the novel HFQSME grouting material for deep high-stress fractured rock mass

In order to control the surrounding rock of deep high-stress roadways, a new prestressed anchor-grouting reinforcement method was proposed with an engineering background of the 1780 ventilation roadway of Shiyakou Coal Mine. A high-fluidity quick-setting micro-expansion (HFQSME) grouting material had been developed through superplasticizer, accelerator, and expansion agent. The results showed that the optimal ratio of HFQSME grouting material was superfine Portland cement of 95%, superplasticizer of 0.5%, accelerator agent of 0.5%, expansion agent of 5.0%, and water-binder ratio of 0.4. The fluidity, initial setting time and expansion rate of the grouting material were 47cm, 41minutes and 0.12%, respectively. The grouting reinforcement effect of superfine slurry and HFQSME grouting material on rock mass with different degrees of fragmentation was investigated. The peak strength of rock mass with two degrees of fragmentation reinforced by HFQSME grouting material was 166% and 233% higher than that of superfine slurry. The macro reinforcement effect of HFQSME grouting material on the surrounding rock of deep high-stress roadway was evaluated through industrial testing. The prestressed anchor grouting method was used to improve the original support design scheme, and data monitoring and analysis were conducted on site. Compared with the original supporting scheme, the deformation of the 1780 ventilation was significantly reduced. Therefore, HFQSME grouting material had good adaptability for the surrounding rock of deep high-stress roadways.

Experimental and simulation study of magnesium phosphate cement two-liquid grouting materials

Magnesium phosphate cement (MPC) has a promising application in grouting. This study drew on the traditional cement-waterglass two-liquid grouting model. Creatively, the two main reaction components of MPC, dead-burned magnesium oxide and phosphate, were applied to the grouting field in a two-component liquid form. At the same time, through proportioning adjustment and experimental testing, we obtained A\B liquid components, which can be stabilized. In addition, MPC slurry was compared with the traditional grouting material, silicate cement slurry, to demonstrate its superiority. Finally, we simulated the grout diffusion process of the mixed slurry using the two-phase Darcy's law module of COMSOL Multiphysics subsurface fluids. The results show that the mixed slurry with a magnesium phosphate ratio of 1/3, a magnesium–boron ratio between 5% and 10%, and a water–cement ratio of 0.2–0.5 has better stability and mobility. Under the same fluidity, its strength is much higher than that of common silicate cement slurry and has good injectability. MPC was subjected to two-fluid grouting to take advantage of its fast-hardening and early-strengthening properties, while also improving its stability and fluidity. This study provided a theoretical foundation for the application of MPC.

Effect of nano-Al2O3 on the mechanical and microstructural properties of cement-based grouting material

The mechanical properties and microstructure of cement-based grouting materials are important parameters affecting the quality of geotechnical engineering, which are limited by the properties of added materials. At present, the exploration of nanomaterials has become the development trend of cement-based grouting materials. The results showed that NA can significantly improve the strength of NCBS. The most pronounced effect was observed when the dosage of NA was 1 %; compared with the control group, the strength increased by up to 45.2 %. NA particles accelerate the hydration reaction rate between cement and fly ash, generating a large amount of hydration products to fill the internal voids of NCBS. When the content of NA was 2–4 %, the strength gradually decreased with an increase in the amount of NA addition. The catalytic and microaggregate effect of the NA particles were the primary contributors to the improved NCBS mechanical properties. Aggregated NA particles were the main cause of the decrease in strength. Acicular ettringite, fibrous calcium silicate hydrate, and NA particles are the dominant components that effect the strength and microstructure of NCBSs. By comparing the relationship between NA and the strength of NCBS and the relationship between the curing age and the strength of NCBS, it was found that NA can better reflect the compressive strength of NCBS, and the correlation degree of NA to the strength of NCBS is 76 % higher than that of the curing age.

Eco-Friendly Shield Muck-Incorporated Grouting Materials: Mix Optimization and Property Evaluation for Silty Clay Tunnel Construction

As shield tunnels increase, managing shield muck strains construction and the environment. To mitigate this problem, shield muck replaced bentonite in silty clay to improve synchronous grouting slurry. Initially, the physical attributes and microstructural composition of shield muck were obtained, alongside an analysis of the effects of the muck content, particle size, and general influencing factors on the slurry properties through standardized tests and regression models. Subsequently, leveraging three-dimensional response surface methodology, admixture interactions and multiple factor impacts on the slurry were explored. Finally, utilizing the SQP optimization technique, an optimal slurry blend ratio tailored for actual project needs was derived for improved muck slurry. The findings reveal with the decreasing bleeding rates as the muck content rises, the particle size diminishes. An inverse relationship exists between the muck content and slurry fluidity. At soil–binder ratios below 0.6, a decrease in the soil–binder ratio intensifies the influence of the water–binder ratio on the slurry density, bleeding rate, and setting time. The fly flash–cement ratio inversely correlates with the slurry bleeding rate, while the ratio greater than 0.6 is positively correlated. For muck particle sizes under 0.2 mm, the fly flash–cement ratio inversely impacts the density, while over 0.2 mm, it correlates positively. The optimal proportion for silty clay stratum synchronous grouting slurry, substituting muck for bentonite, includes a water–binder ratio of 0.559, binder–sand ratio of 0.684, fly flash–cement ratio of 2.080, soil–binder ratio of 0.253, particle size under 0.075 mm, and water-reducing admixture of 0.06.

Heat transfer performance analysis of medium - deep coaxial borehole heat exchanger (CBHE): combination of heat extraction operation test and numerical simulation

Abstract Geothermal energy is a clean and renewable energy source that can effectively reduce carbon emissions. Coaxial borehole heat exchanger (CBHE) is a crucial component of the geothermal mining system. To understand the heat transfer mechanism of a CBHE and to design its construction, this paper analyzes the geotechnical thermal response characteristics of CBHE under constant power conditions. COMSOL was used to simulate the performance of the heat exchanger during intermittent operation in both summer and winter. The results indicate that the inlet water temperature and the thermal conductivity of the grouting material have a weak impact on the energy efficiency coefficient of the heat exchanger. The energy efficiency coefficient can increase by about 22% when the inner pipe's thermal conductivity is lower. The temperature difference between the medium flowing into the inner pipe at the bottom of a shallow cased buried pipe and the medium flowing out of the inner pipe defines the thermal short circuit value. The influence on the thermal short circuit value is on the order of the inner pipe thermal conductivity, grouting material thermal conductivity, and the inlet water temperature. The fluctuation of soil temperature in the summer is greater than that in the winter, the soil temperature of shallow-buried pipes is easier to recover in the winter. The characteristic law obtained in this paper provides a valuable reference for the scientific design of CBHE.

Determination of thermal properties of grouting materials for borehole heat exchangers (BHE)

Thermal properties of grouting materials for borehole heat exchangers (BHE) are currently analysed with varying measurement methods and analysis procedures, resulting in difficulties when comparing values of different studies. This study therefore provides the first comprehensive investigation of different analysis procedures by systematically comparing the influence of the measurement method and the sample preparation on the determination of the thermal conductivity and the volumetric heat capacity. Seven dissimilar grouting materials with varying water–solid ratios (W/S) and compositions are analysed. The thermal conductivities of the materials range between 0.9 and 1.8 W m−1 K−1 (transient plane source method, TPS). The volumetric heat capacities range between 3.01 and 3.63 MJ m−3 K−1 (differential scanning calorimetry, DSC). From the findings of this study, a standardised analysis of grouting materials is provided which suggests mixing of the grouting material at a high mixing speed and sample curing under water for 28 days at room temperature. The benefits of calculating the volumetric heat capacities of grouting materials from the specific heat capacities of dry samples measured with the DSC, the water content and the bulk density are demonstrated. Furthermore, an estimation procedure of volumetric heat capacity from the W/S and suspension density with an uncertainty of smaller ± 5% is provided. Finally, this study contributes to consistency and comparability between existing and future studies on the thermal properties of grouting materials.

Study on the working performance and microscopic mechanism of high-performance grouting material (HPGM) reinforced dense fine sand layer

To address the challenges of small diffusion radius, low early strength and long setting time of traditional cement grout in dense fine sand layer, based on the synergistic mechanism, a novel high-performance grouting material (HPGM) was developed using ground granulated blast-furnace slag (GGBS), ultra-fine fly ash (UFFA), and ultra-fine Portland cement (UFPC) as raw materials. Firstly, Laboratory experiments were conducted to investigate the working performance of HPGM under varying proportions. Secondly, based on the self-designed advanced small pipe grouting full-scale test device, the diffusion performance and reinforcement characteristics of HPGM under varying proportions were analyzed. Finally, the XRD and SEM testing methods were employed to elucidated the hydration mechanism of the HPGM. The test results indicate that as the mass ratio of GGBS to UFFA decreases, there is a gradual increase in hardening rate, fluidity and setting time of HPGM. Additionally, the unconfined compressive strength (UCS) initially increase before decreasing. Furthermore, with the decreased mass ratio of GGBS to UFFA, the HPGM diffused in dense fine sand layer through compaction-splitting, permeation-splitting, and splitting grouting processes. The hydration products of the HPGM primarily consist of C(-A)-S-H, AFt, and Ca(OH)2, when the mass ratio of GGBS to UFFA falls within the range of 4:2–3:3, the UFFA facilitates the AFt hydration products in significant quantities. Its cementation and filling effect lead to the formation of a dense microstructure in the soil, resulting in a substantial reduction in permeability coefficient and a marked increase in UCS. The research findings can offer high-performance grouting material for underground engineering construction while also presenting innovative ideas for resource utilization from solid wastes like GGBS and UFFA.